Explanation: A regenerative, oscillating-detector, by its very nature, generates its own radio frequency (RF) signal to achieve high sensitivity. When this circuit is directly coupled to an antenna, the antenna acts as an efficient radiator for this internally generated RF signal. This radiated signal, even if low power, can be picked up by nearby receivers. If its frequency is close to another carrier frequency being received, the two signals will mix or "beat" together in the receiver's front end, creating audible whistle-like interference, known as heterodyning. This is why answer A is correct. B is incorrect because the circuit *is* oscillating and coupled to an antenna, designed to radiate. C is incorrect as the energy radiated is typically low, though sufficient to cause significant local interference.